AWWA DSS71287

This powerpoint presentation begins by providing a brief overview of the difficulties in locating closed valves in a distribution system. Methods for finding closed valves include: get on the valve and operate; use hydraulic model to find closed valves; and, closed valves often found in calibration. Reasons why closed valves don't reveal themselves include: los velocity; change in head loss and pressure is negligible; and, a closed valve shows itself during fires, shutdowns, and when you really need it open. Problems with boundary valves (BVs) include: 10% of existing BVs not sealed; and, 10% of proposed BVs won't seal. Problems of internal valves include: 12% of internal valves meant to be open are shut; and, if not addressed, can form new leakage management area; can accidentally cut supply to customers; make customer fire systems non-compliant; and, street hydrants operate at flows less than desired capacity. Includes tables, figures.